Recently, there has been an increasing demand for exterior materials for electric and electronic products or automobiles having high functionality and high performance. In particular, there is increasing demand for exterior materials that ensure flame retardancy together with good scratch resistance and pleasant tactile texture.
As commercially available resins capable of exhibiting scratch resistance, acrylic resins, specifically polymethyl methacrylate (PMMA) resins, have excellent transparency, weather resistance, mechanical strength, surface gloss, adhesion, and the like. However, acrylic resins have drawbacks in that impact resistance and flame retardancy are very poor.
In order to achieve both scratch resistance and flame retardancy, it is proposed to add a flame retardant to impose flame retardancy in preparation of polymethyl methacrylate (PMMA) resins having good scratch resistance of a pencil hardness level of 3H to 4H. In this case, however, it is necessary to add a large amount of flame retardant. As a result, the flame retardant monomer can escape from the resins, which can cause environmental problems and deterioration in mechanical properties of the resin.
In addition, the acrylic resin, specifically a polymethyl methacrylate (PMMA) resin, can be mixed with a polycarbonate resin exhibiting good mechanical strength and flame retardancy to provide good scratch resistance and flame retardancy. However, due to high index of refraction of the polycarbonate resin, the polymethyl methacrylate resin can suffer from deterioration in transparency and colorability when mixed with the polycarbonate resin. Moreover, in order to have good compatibility with the polycarbonate resin, the acrylic resin is required to have a high index of refraction.